This invention pertains to yield monitors for grain harvesters. Increasing emphasis is being placed on determination of crop yields as harvesting is being accomplished, particularly when the crop yield data is integrated with precise mapping of fields through use of a global positioning satellite receiver.
In the existing onboard yield measurement systems available for grain harvesters, harvested grain weight is measured by use of a vertical impact plate positioned in the path of grain being discharged from an enclosed chain driven paddle conveyor commonly referred to as a clean grain elevator of the grain harvester or combine. Such a measurement device is described in U.S. Pat. No. 5,343,761. This system has shortcomings, namely baseline drift which occurs in the sampling must be corrected as described in U.S. Pat. No. 5,594,667. Also calibration is required at varying rates of flow, and inaccuracy cannot be eliminated because test weight measurements of the grain are not available on a real time basis. For example, with existing apparatus, the weight of corn harvested is presumed to be fifty-six pounds per bushel at fifteen percent moisture while the actual test weight of the corn may be much different. The condition and spacing of conveyor paddles, the varying slope of the combine as it traverses a field, and the speed of the clean grain elevator also can affect accuracy. A need exists for a yield measurement system which periodically samples test weight of grain being harvested and measures flow rate volume accurately at varying flow speeds, in order to provide accurate input data for real time calculation of yield rates within a field being harvested.
As part of the monitoring of crop yield, apparatus has been developed to measure crop moisture of samples of grain within the grain harvester or combine, including devices which mount to the exterior of the clean grain elevator of the grain harvester or combine. The clean grain elevator elevates grain from the separator of the combine to the onboard storage tank of the combine which is located at the top of the combine. Current moisture sensors collect a sample of grain from the lift side of the clean grain elevator through an opening in the elevator housing and pass the grain into a vertical chamber in which a moisture sensor has been mounted. Periodically the chamber is emptied by operation of a motor driven paddlewheel or auger which carries the grain from the chamber and drops it through an exhaust duct into the return side of the elevator housing so that a new sample can enter the chamber for moisture testing. Once the combine is shut down, the operator must remember to energize the paddlewheel or auger of the moisture test apparatus to empty it. If that is not done, grain will remain in the chamber and be subject to freezing or deterioration which may result in clogging of the moisture test apparatus. Downtime and inconvenience result from such clogging, along with the danger from manually removing clogged grain from the moisture test apparatus. A need exists for an elevator mount moisture sensor which resists clogging and which may be mounted on many different makes and models of harvester.
A yield monitoring system for a grain harvesting combine is disclosed. The system includes a volume monitor, a moisture monitor, a test weight monitor, a ground speed monitor, and a computer which receives signals from each monitor and continuously derives harvested grain yield rates from those signals, displays the yield rates on a visual display and records the yield rate information for later recall and transfer to other computers. A GPS receiver linked to the system enables it to map yields geographically in the harvested field.
A volume monitor is positioned at the exhaust spout at the top of the clean grain elevator. The volume monitor receives all grain exiting the clean grain elevator and passes it on to a fountain auger that delivers it to the on board storage tank of the grain harvester combine. The volume monitor includes a receiving hopper which collects grain exiting the clean grain elevator discharge port. An ultrasound level monitor is mounted above the hopper to detect and monitor the height of grain in the hopper. The hopper includes a lower discharge chute which directs grain onto a paddlewheel which may be driven at selectively varying rotational speeds. The speed of rotation at which the paddlewheel is driven is determined by a controller which causes the paddlewheel to turn sufficiently fast to maintain the grain at a steady level determined by the level monitor. Hence when grain in the hopper is below the level determined by the level monitor, the paddlewheel is stopped and when grain rises above the height determined by the level monitor, the paddlewheel is driven sufficiently rapidly so that grain in the hopper remains at the level determined by the level monitor. The angular displacement of the paddlewheel is measured and a signal is generated which is provided to the computer. Because the volume capacity of the paddlewheel to pass grain is predetermined, the angular displacement over time of the rotation of the paddlewheel provides information from which volume of harvested grain over a time interval may be calculated.
The length of time interval for volume measurement may be selected over any range but a convenient interval for effective measurement is from one to five seconds and in practice, the preferred interval is two seconds, that is, the volume monitor provides volume of grain exiting the clean grain elevator in two second increments, and the moisture and test weight data are polled by the computer every two seconds.
The moisture monitor mounts to the exterior of the clean grain elevator within the combine. A flexible entry duct which is open to the interior of the lift side of the grain elevator is joined to the upper end of a housing in which a moisture sensor is mounted. The housing is oriented vertically to hold a column of grain to be moisture tested. The lower end of the housing opens to a non-motorized, compartmented wheel preferably housing equally sized circumferential compartments of preselected size. The lower end of the housing is sized so that only one compartment of the wheel may receive grain from the housing at one time. Free rotation of the wheel is prevented by a stop mechanism which in practice may be a plunger which extends toward the wheel to prevent its rotation. Momentary retraction of the plunger is controlled by a signal from a level sensor which is mounted in the housing above the moisture sensor to sense when grain in the housing reaches the level of the level sensor. When grain is sensed by the level sensor, the plunger is momentarily de-energized and retracts from the wheel, allowing the wheel to turn an incremental one-quarter rotation. Immediately thereafter, the plunger is energized and extends to stop further rotation of the wheel. Rotation of the wheel allows a fixed volume of grain to exit the housing which may then be refilled by grain falling from the lift side of the elevator into the housing through the entry duct. The moisture sensor detects moisture content in the column of grain and when polled by the computer provides a signal indicative of the level of moisture in the grain.
After the grain passes the compartmented wheel, it may be exhausted into the return side of the elevator through a flexible exhaust duct, or it may be passed into a test weight measurement assembly which may be located below the wheel so that the grain from the wheel may fall into a container of known tare weight. The grain in the compartment of the compartmented wheel under the lower end of the housing is of a predetermined volume. This known volume of grain falls into the container of the test weight measurement assembly. The container is suspended from a load cell which determines the weight of the grain which is in the container of the test weight measurement assembly.
In order to improve accuracy of the test weight measurement, a second load cell is mounted near the first load cell with the second load cell suspending a known weight equal to the standard test weight of a preselected volume of the grain to be harvested plus the known tare weight of the empty container. Coupling the test weight load cell output with the inverse of the output of the second load cell suspending the known weight allows elimination of weighing errors due to vibration or jiggle of the load cells within the grain harvesting combine. Output of the combined load cells equals the difference in weight between the measured test weight and the standard test weight.
Once the weight of the known volume of grain is determined and grain is sensed by the level sensor, the container empties into the exhaust duct which returns the tested grain to the return side of the elevator. Emptying of the container may be done by providing the container with a trap door bottom which may be released to swing away and allow the grain to pass. After the container has been emptied, the trap door bottom closes so that the container may receive the next sample of grain to be weighed. The trap door of the container opens and closes each time before the compartmented wheel is released to turn a quarter turn. With the test weight monitor option, the control signal from the level sensor to the compartmented wheel is delayed until the container is emptied and the trap door closed.
The particular moisture monitor of the present invention has a vertically oriented housing for temporarily holding a column of grain to be moisture tested. The use of flexible ducting from the lift side of the clean grain elevator to the housing, and also from the discharge from the moisture monitor to the return side of the elevator allows the moisture monitor to be installed on many differing configurations of clean grain elevator which may be found in different makes and models of grain harvesting combines. The novel discharge mechanism of the moisture monitor additionally provides a moisture monitor housing which automatically is emptied upon equipment shut down because the stop mechanism plunger which restrains the wheel from rotation is retracted when it is de-energized, thereby permitting the wheel to rotate freely to empty the housing of its column of grain. The test weight unit also empties upon shut down and the grain falls into the return side of the clean grain elevator.
A global positioning system (GPS) receiver is stationed on the grain harvesting combine to receive and store position information as well as to receive change-in-position information from which to calculate direction and velocity information. The velocity information from the GPS receiver is transmitted to the computer to be used in the yield calculations. As an alternative, ground speed of the grain harvesting combine may be obtained from well known transducer means mounted in the drive gear of the combine. The electronic output of such a transducer would be delivered to the central computer to be used for the ground speed data.
As the computer receives the volume data, the moisture content data, the weight per bushel (test weight) data, the ground speed data, having been calibrated for the swath of the harvester cutting head, the computer can calculate the area harvested and the current yield in pounds (and bushels) per acre of dry grain equivalent, transfer the data to the display for display to the operator, and transmit the data to a non-volatile memory device such as magnetic media or optical media (CD-ROM). Because the system is preferably integrated with GPS data, mapping of fields by yield may be accomplished.
It is an object of the invention to provide a yield monitoring system for a grain harvester which provides real time yield information at a high level of accuracy independent of harvester variables.
It is a further object of the invention to provide a yield monitoring system which determines actual test weight in pounds per bushel of crop grain as it is harvested.
It is a further object of the invention to provide a yield monitoring system which provides an accurate measurement of volume of crop grain being harvested per unit of time.
It is yet a further object of the invention to provide a yield monitoring system which generates real time yield data at known field locations.
It is yet another object of the invention to provide a moisture monitor which mounts to many different combine clean grain elevators without substantial modification.
It is yet another object of the invention to provide a moisture monitor which prevents clogging of the moisture monitor when it is not in operation.
It is a further object of the invention to provide a weighing apparatus using two load cells to eliminate weighing errors due to vibration of the combine in which weighing of the grain is to be accomplished.
These and other objects of the invention will become apparent from examination of the detailed description and drawings included in this specification.